Hi everyone!
Eugene here from the APAC Customer Support Specialist team!
With business units, you’d be able to segment out to which business unit that contact record is and view the subscription preferences page accordingly:
For each marketing email that you have, you’d want to change the office location in the footer module accordingly to which business unit the marketing email is in.
Once you’ve changed that office location, the preference/subscription page the contact record would see if they click into the link would display the business unit’s accordingly 
A good point to note with this feature, if you click on the “send test email”, the test email would default to your account’s main business unit, so the display would be slightly different from what is expected. However, if you go ahead and send the email live to a contact record (you could send it to a sample contact record), the preference/subscription link would direct to the correct business unit as expected